The present invention relates to a device for detecting the abnormality of a pick-up head for an optical recording/reproducing apparatus.
In an apparatus for optically recording and reproducing information, information is recorded on a recording medium and erased by emitting a light beam from an optical pick-up head to the medium. The recorded information of the medium is reproduced by detecting the light beam reflected from the medium, and tracking and focus servo controls are performed. A predetermined optical system is used to emit the light beam to the medium and to detect the reflected light. The optical system is constructed by a lens and a prism. When dusts are adhered to the optical members, the amount of light beam emitted from the head decreases. Thus, information is not completely recorded in a recording mode, and a reproducing error is generated in a reproducing mode. Further, a serious defect occurs in the feedback loops of tracking and focusing servo mechanisms.
Since the object facing surface of the objective lens of the optical system of the optical pick-up head is exposed with a recording medium, dusts tend to feasibly adhere to the lens surface. A user does not note the dusts adhered to the lens. Therefore, means for detecting the abnormality of a pick-up head due to the dusts adhered to the optical system is desired.